10w solar system operation and maintenance common faults and solutions

- Feb 13, 2019-

1. The inverter screen is not displayed.


Fault Analysis: Without DC input, the inverter LCD is powered by DC.


possible reason:


(1) The panel voltage is not enough. The operating voltage of the inverter is 100V to 500V. When the voltage is lower than 100V, the inverter does not work. The solar module voltage is related to solar irradiance.


(2) The PV input terminal is reversed. The PV terminal has positive and negative poles. It must correspond to each other and cannot be connected in series with other groups.


(3) The DC switch is not closed.


(4) When the solar panels are connected in series, one of the connectors is not connected.


(5) A solar module is short-circuited, causing other strings to not work.




Use the multimeter voltage file to measure the DC input voltage of the inverter. When the voltage is normal, the total voltage is the sum of the voltages of the PV modules. If there is no voltage, check whether the DC switch, terminal block, cable connector, components, etc. are normal. If there are multiple modules, separate the tests separately.


If the inverter is used for a period of time and no cause is found, the inverter hardware circuit is faulty and needs to be contacted for after-sales.


2, the inverter is not connected to the network


Fault analysis: The inverter and the grid are not connected.


possible reason:


(1) The AC switch is not closed.


(2) The inverter AC output terminal is not connected.


(3) When wiring, loosen the upper row of the inverter output terminal block.


Solution: Use the multimeter voltage file to measure the AC output voltage of the inverter. Under normal conditions, the output terminal should have 220V or 380V voltage. If not, check whether the terminal is loose, the AC switch is closed, and the leakage protection switch is broken.


3, PV overpressure


Fault analysis: DC voltage is too high alarm.


Possible cause: The number of solar panels connected in series is too high, causing the voltage to exceed the voltage of the inverter.


Solution: Because of the temperature characteristics of the solar module, the lower the temperature, the higher the voltage. The input voltage range of the single-phase string inverter is 100-500V. It is recommended that the voltage after the string is between 350-400V. The input voltage range of the three-phase string inverter is 250-800V. Suggested 600-650V, in this voltage range, the inverter is more efficient, and it can generate electricity when the irradiance is low in the morning and evening, but it does not cause the voltage to exceed the upper limit of the inverter voltage, causing an alarm and stopping.


4, isolation failure


Fault analysis: The insulation resistance of the photovoltaic system to ground is less than 2 megohms.


Possible causes: Solar modules, junction boxes, DC cables, inverters, AC cables, terminals, etc., where there is a short circuit to the ground or damage to the insulation. The PV terminals and the AC wiring housing are loose, resulting in water ingress.


Solution: Disconnect the grid, inverter, and check the resistance of each panel to the ground in turn, find the problem, and replace it.


5, leakage current failure


Fault analysis: The leakage current is too large.


Solution: Remove the PV array input and check the peripheral AC grid. The DC terminal and the AC terminal are all disconnected, and the inverter is powered off for more than 30 minutes. If you can recover it, continue to use it. If it cannot be recovered, contact the after-sales technical engineer.


6, the grid error


Fault Analysis: The grid voltage and frequency are too low or too high.


Solution: Use a multimeter to measure the grid voltage and frequency. If it is exceeded, wait for the grid to return to normal. If the grid is normal, the inverter detects the power failure of the circuit board. Please disconnect the DC terminal and the AC terminal completely, and let the inverter power off for more than 30 minutes. If you can recover it, continue to use it. If it cannot be recovered, contact the after-sales service technical engineer.


7, inverter hardware failure


Divided into recoverable faults and unrecoverable faults.


Fault analysis: The inverter circuit board, detection circuit, power circuit, communication circuit and other circuits are faulty.


Solution: The above hardware failure occurs in the inverter. Please disconnect the DC terminal and the AC terminal completely, and let the inverter power off for more than 30 minutes. If you can recover it, continue to use it. If it cannot be recovered, contact the after-sales technical engineer.


8, the system output power is too small


The desired output power is not achieved.


Possible causes: There are many factors affecting the output power of PV power plants, including solar radiation, tilt angle of solar cell components, dust and shadow blocking, and temperature characteristics of components.


The system power is too small due to improper installation of the system configuration.


Common solutions are:


(1) Before installation, check if the power of each component is sufficient.


(2) Adjust the installation angle and orientation of the components.


(3) Check the components for shadows and dust.


(4) If the voltage is within the voltage range after the components are connected in series, the system efficiency will decrease if the voltage is too low.


(5) Before installing the multi-channel string, check the open circuit voltage of each string, the difference is no more than 5V. If the voltage is wrong, check the line and connector.


(6) When installing, it can be accessed in batches. When each group is connected, the power of each group is recorded, and the power difference between the strings is not more than 2%.


(7) The ventilation of the installation place is not smooth, the heat of the inverter is not spread out in time, or it is exposed directly in the sunlight, causing the temperature of the inverter to be too high.


(8) The inverter has dual MPPT access, and each input power is only 50% of the total power. In principle, the power of each design should be equal. If only one MPPT terminal is connected, the output power will be halved.


(9) The cable connector is in poor contact, the cable is too long, the wire diameter is too thin, there is voltage loss, and finally the power loss occurs.


(10) The grid-connected AC switch capacity of the PV power station is too small to meet the inverter output requirements.


9, AC side overvoltage


If the impedance of the power grid is too large, the user side of the photovoltaic power generation cannot digest it. When the power is sent out, the impedance is too large, causing the voltage on the output side of the inverter to be too high, causing the inverter to be protected from shutdown or derating.


Common solutions are:


(1) Increase the output cable because the thicker the cable, the lower the impedance.


(2) The inverter is close to the grid point, and the shorter the cable, the lower the impedance.